Grinding and polishing machine for stones.



Patented Jan. 6, 1914.

APPLICATION FILED SEPT. 16, 1912.

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GRINDING AND POLISHING MACHINE FOR STONES.

Specification of Letters Patent.

Patented Jan. 6, 1914.

Application filed September 16, 1912. Serial N 0. 720,582.

To all whom it may concern Be it known that I, Gnono Boi-innvonn, manufacturer, a subject of the Emperor of Germany, and residing at Lindenfels, Odenwald, in the Grand Duchy of Hesse, German Empire, have invented new and useful Improvements in Grinding and Polishing Machines for Stones, of which the following is a specification.

This invention has for its object a grinding and polishing machine with a rotating head piece supported on a linked arm system so that it can be moved mechanically over the workpiece to be ground while being pressed thereon with a spring pressure. The

machine is specially suitable for polishing stone of various kinds including for instance, marble, syenite, granite and the like. The machine works in an automatic manner and produces an absolutely even and regular surface on the workpiece.

The invent-ion is illustrated by way of example in one form of construction in the accompanying drawings, in which Figure 1 is a front View of the machine. Fig. 2 is a side view. Fig. 8 shows a vertical section of the support for the grinding and polishing head drawn to a larger scale, and Fig. 4c shows a diagram of the path of movement of the grinding and polishing head.

In the drawings a indicates a swinging arm supported on a vertical shaft 7) which is carried in a suitable bracket or stand.

011 the end of the arm a is pivoted an extension arm 0 whose outer end carries the shaft (Z of the interchangeable grinding head a. The shaft 61 is driven in any convenient manner, for instance by means of belts and belt pulleys on the shafts b and (Z, and on the intermediate shaft which formsthe pivoting connection between the arms a and c. The shaft (Z of the polishing head is made adjustable vertically in order to permit of the adjustment of the grinding head on the workpiece. The adjustment is effected by means of a hand wheel working on the screw threaded upper end of the shaft (Z and resting against the top of the bearing sleeve h. A spring 9 is provided in order to press the grinding head in a resilient manner against the workpiece, and the grinding head is connected to its shaft by means of a joint such as a universal joint which will allow some freedom of movement in all directions relatively to the axial line of the shaft.

The shaft d is driven by means of a pulley mounted on the bearing sleeve h. The sleeve h is held against longitudinal movement by its head at the lower end and by the boss of the pulley atthe upper, as seen in Fig. 3. The shaft of, while free to move vertically, is arranged to be carried around by the sleeve h, for which purpose a key or feather 7: is inserted in the sleeve h engaging in a corresponding keyway 70 formed in the shaft d. Of course the key might be in the shaft d and the keyway in the sleeve while securing the same result.

The spring 9 which presses down the grinding head 6 is shown in Fig. 3 as being a spiral spring surrounding the lower part of the shaft (Z, and pressing at the top against the lower end or head of the sleeve h, while the lower end of the spring presses against a projection on shaft d or on the attachment member for the grinding head 6.

The shaft d can be raised or lowered as is evident by turning the hand wheel f, and thus the spring 9 can be more or less compressed as may be desired in order to regulate the pressure of the grinding head on the workpiece. The grinding head can be completely lifted ofl the workpiece also by turning the hand wheel f. In order to guide the grinding head in its movements over the workpiece the vertical end portion of the arm a is embraced by the end of a link arm Z which is pivotally supported on a slide member working in guides m and actuated by means of a rod n whose other end is pivoted on an adjustable crank pinon a disk 0 so that the length of the stroke can be varied. The link arm Z with its actuating mechanism and guides m is supported on a slide 79 which is mounted to work to and fro in a stationary bed in a direction at right angles to that of the movement of the supporting pin of the arm Z. The movement is imparted to the slide 79 by means of a screw stem Q which is driven by a reversing 'ear alternately in one direction of rotation End the other. In the example of construction shown a direct and reverse pulley drive is used for actuating the spindle d, the belts working on fast and loose pulleys as usual. Any suitable belt shifting mechanism may be employed for changing over the drive. For instance, the belts may he guided in forks attached to a longitudinally movable rod 1', which rod carries adjustable stops 8 adapted to be struck so as to effect the shifting of the belts when the slide p reaches either end of its path of movement. In this way the rod 1' is moved first in one direction and then in the other in order to shift over the belts and to bringone or other into the driving position, so that the slide 79 is moved steadily to and fro in its guide bed. The length of movement is adjusted by altering the position of the stops 8 on the rod 0.

A shaft t is arranged parallel to the spindle q, the said shaft being provided with a worm u gearing with a worm wheel '0 by means of which the crank disk 0 is driven and the reciprocating movement is imparted to the pivot of the link arm Z. The Vertical shaft to which carries the crank disk 0 and the worm wheel o is supported in bearings in the slide 79 so as to move therewith, and hence either the worm a must be supported by a keyway on the shaft 25 so as to move longitudinally with the slide 70, or the shaft t itself must be capable of longitudinal movement. In the example of construction shown, the shaft 25 is fixed longitudinally and is formed with a keyway in which a key projecting inwardly from the worm o engages, while the said worm is held between two projecting pieces or bearings in the slide 72 so. as to be carried to and fro therewith.

If the two movements at right angles of the slide and the support for the arm Z respectively were synchronized, 2'. 6., if the one movement corresponded exactly with a certain number of the other movements, a plain zigzag movement would be imparted to the grinding head 6. This head therefore would always move to and fro in the same path over the face of the workpiece and the resulting surface would be irregular because the pressure could not be made equal at all points over the grinding and polishing face. The shaft t is therefore driven independently of the spindle 1 so that the grinding head may be caused to move to and fro in'a closed path, as indicated, for instance in Fig. 4, in which a number of zigzag movements parallel one to another are described.

The shaft 2. is shown as being driven by bevel gearing from the vertical shaft 6 of the swinging arm a and the said shaft 1) is driven by a. belt drive or the like, The bQYe-l wheels :1 2 which transmit the drive from the shaft 7 to the shaft 25 are so dimenturning movements of the grinding head a and the thereto.

The separate driving of the slide 79 and of the support of the arm Z in the manner described prevents the grinding head from moving in a simple zigzag path, but although the movements will be parallel to one another they will usually repeat after a certain number of to and fro movements of the slide 79, as indicated in Fig. 4. The repeating of the path of movement at such long intervals will be a matter of no consequence, but such a movement of the grinding and polishing head will insure that a perfectly even and smooth surface will be given to the workpiece and there will be no irregularities or faults. Instead of driving the shafts g and 2? through separate belt gearing in order to avoid synchronism in the rotation thereof, positive gearing may be used with different numbers of gear teeth as will be evident, the only requirement being that the path of the center of the guiding head shall not repeat itself until after a very considerable number of reversing movements which will insure that the workpiece is worked over in an even manner. The two movements at right angles will be made such that the shaft (Z will never move beyond the edges of the workpiece, but the total area described by the diagram, Fig. 4, will fall well within the borders of the workpiece. It will thus be seen that I impart movement to the grinding or polishing head in angular courses or lines of travel.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. A stone or like grinding or polishing machine comprising in combination, a grinding head, linked mechanism for said head comprising a main arm having a fixed driven pivot, an extension arm pivoted to said main arm and carrying said head at its free end, belt transmission means on said mechanism for revolving said head, means for moving said head to and fro in one line of travel, and means for moving said head to and fro reversing movements imparted in a line of travel angular to said first named line of travel, substantially as described.

2. A stone or like grinding or polishing machine comprising a grlnding head and a shaft therefor, a sleeve carrying said shaft and head, an actuating sleeve non-rotatively travel during rotation of said head, substanbut slidably connected With said shaft and tially as described. 10 rotatively mounted in said carriage, driving In testimony whereof I aflix my signature means connected with said actuating sleeve in presence of tWo Witnesses.

to rotate said head, means operatively asso- GEORG BOHRINGER, ciated With said shaft and actuating sleeve Vvitn s s;

for adjusting said head, and devices moving S. H. SHANK,

said head to and fro in angular lines of JosEPI-I HEIFFER.

Copies of this patent may be obtained for five cents each, by addressing the Gommissionei' of Patents. Washington, D. G. 

